Universal mobile telecommunications system (UMTS) is a 3rd generation (3G) asynchronous mobile communication system operating in wideband code division multiple access (WCDMA) based on European systems, global system for mobile communications (GSM) and general packet radio services (GPRS). A long-term evolution (LTE) of UMTS is under discussion by the 3rd generation partnership project (3GPP) that standardized UMTS.
The 3GPP LTE is a technology for enabling high-speed packet communications. Many schemes have been proposed for the LTE objective including those that aim to reduce user and provider costs, improve service quality, and expand and improve coverage and system capacity. The 3GPP LTE requires reduced cost per bit, increased service availability, flexible use of a frequency band, a simple structure, an open interface, and adequate power consumption of a terminal as an upper-level requirement.
The purpose of a radio resource control (RRC) connection establishment procedure is to establish an RRC connection. RRC connection establishment involves signaling radio bearer 1 (SRB1) establishment. The RRC connection establishment procedure is also used to transfer an initial non-access stratum (NAS) dedicated information/message from a user equipment (UE) to an evolved UTMS terrestrial radio access network (E-UTRAN). The E-UTRAN applies the RRC connection establishment procedure to establish SRB1 only.
The UE may transmit an RRC connection request message to initiate the RRC connection establishment procedure. The RRC connection request message may include establishment cause for the RRC connection request as provided by the upper layers. An eNodeB (eNB) may proceed or reject the RRC connection request based on the establishment cause included in the RRC connection request message.
Currently, various establishment causes are defined in the RRC connection request message. However, according to a situation, configurable cause value may be needed.